We can clearly see that the blank is preceded by the definite article "the". Now, a superlative degree usually comes with “the” before it.

For example: The boy is the tallest in his class.

So, it should be filled with a superlative degree. “Poorest” is the only superlative degree here. "Poor" is the positive degree and "poorer" is the comparative degree.

"Pooring" can be used as the noun meaning Impoverishment.

 

The blank needs to be filled with a verb.

Now, "is" is used in the continuous tense as an auxiliary verb. “Is / am / are + verb + ing” is the correct structure of the progressive or continuous tense.

For example: I am doing my homework.

So, “is” before the blank is a hint that “-ing” form should come in the blank.

The subject of the clause is “nations” - a plural noun, so the blank should be filled with a plural verb only. Only “are” is plural here.

The other options "am", "is", and "was" are singular, thus incorrect.

The verb “base” is usually followed by the preposition “on”. The phrasal verb "base on" means to use particular ideas or facts to make a decision, do a calculation, or develop a theory.

For example: The paper is based on the research of Prof. Chaturvedi.

So, the blank should be filled with the preposition “on”.

The definite article is used before the names ofSome Geographical Areas.

For example: the South Pole, the West, the South, the North East etc.

"World” also refers to the geographical area in general. "Some" is contextually incorrect here. So, “the” should come in the blank.

The underlined part of the sentence isgrammatically correct. 

• The actions of "leaving" and "discovery" happened in past but the denial is happening in the present.

• Thus it must be written in the present tense.

• Also, "Neerav and his uncle" is a plural subject. Thus, the present plural verb "have" is correct to use here.

Let's find out the correct filler for the blank:

• There are two forms of practice: “Practice” and “Practise”.

• “Practice” is a noun that means the actual application or use of an idea, belief, or method, as opposed to theories relating to it.

• “Practise” is a verb that means perform (an activity) or exercise (a skill) repeatedly or regularly in order to acquire, improve or maintain proficiency in it.

• Since the sentence shows the action of practicing mathematics, therefore a verb must be needed here.

• Now with ‘had’ the past participle form of the verb (V3) is used.

• Also, the last option ‘done practised’ is superfluous as practise itself depicts doing of things.

• Thus "practised" will appropriately fill in the blank.

Let us understand the meaning of the given words:- 

• Indifference = unbiased impartial unconcern.
• Concrete = capable of being perceived by the senses; not abstract or imaginary.
• Mediocrity = ordinariness as a consequence of being average and not outstanding.
• Compassion = the humane quality of understanding the suffering of others and wanting to do something about it.

Now, let's find out the correct filler for the blank:

• According to the context of the sentence, we need a positive word.

• After analyzing the meanings of the given words, we can understand the "ideal" can hardly be associated with the words like "indifference", "concrete", or "mediocrity".

• Any of these words cannot make us feel "grateful".

• On the other hand, "Compassion" motivates people to go out of their way to help the physical, mental, or emotional pains of another and themselves.

• Thus, "Compassion" is the most suited for the blank.

Let’s understand the meaning of the given words:-

Insult = speak to or treat with disrespect or scornful abuse. 
Example: He hurled insults at us.

Apply = make a formal application or request. 

Remove = take (something) away or off from the position occupied. 

Offend = cause to feel upset, annoyed, or resentful. 
Example: 17 percent of viewers said they had been offended by bad language.

Offer = present or proffer (something) for (someone) to accept or reject as desired. 

Let’s understand the meaning of the given words:-

Conquest= the process of gaining control of something.

Draw= a game in which no one wins.

Triumph= a great success or victory.

Feat= an act that shows skill and strength.